Patent GB-380928-A (GB)
Title: Improvements relating to the continuous separation of a body from its solution in a liquid
IPC: B01D11/04
Filed: 1931-09-08
Abstract: <PICT:0380928/IV/1> In processes for the separation of a body from its solution in a liquid by extracting it in countercurrent with a solvent insoluble in the liquid in a series of extractions in each of which the solvent and solution are intimately mixed and the mixture decanted, e.g. as described in Specification 307,868, [Class 2 (iii), Dyes &c.], the extractions are effected at or above the boiling-point of the mixture and the substances are mixed in each stage by bubbling the vapours rising from one stage through the liquids in the next stage.  A 25 per cent solution of acetic acid is extracted with methyl cyclohexanone in a column A having a number of double plates each comprising a decantation plate (D1, D2 .. Dn) and an ordinary bubble plate (P1 . . Pn) connected by overflow pipes T1 . . Tn and M1 . . Mn.  Vapours rising from the plate P1 pass upwards through a pipe c2 and through a bubble cap into the liquid on the plate P2.  Each decanting plate, e.g. D2, is connected to a receiver R2 by three conduits b2, c2, d2 by which the levels of the upper and lower layers and the pressures in the chambers R2 and A are equalized.  The lower layer may be extracted from the receiver R2 by a conduit c2 having an adjustable outlet f and may be raised to the mixing plate P3 above it by injection of steam or other known means.  The dilute acetic acid is supported through a pipe g and methyl cyclohexanone through a pipe S, while concentrated acid dissolved in the solvent is recovered through a pipe a and is freed from solvent in any known manner.  The dehydration of a 10 per cent acetic acid solution by means of isopropyl acetate is described with reference to a modified column in which a column as shown in the Figure is superposed on a column forming dehydrating and separating zones. The composition of the mixture which runs on to the first plate of the dehydration zone is 91,8 per cent isopropyl acetate, 4,4 per cent acetic acid, and 3,8 per cent water and the isopropyl acetate being present in sufficient amount to eliminate the water, the dehydrated mixture descends into the separation zone and then into a small auxiliary column whence the acid and acetate are separated readily by their difference in boiling-points.  Examples are also given of the dehydration of acetic acid by a mixture of ethyl acetate and benzene, and also by amyl alcohol.  The process is suitable for the esterification of aliphatic acids as described in Specification 378,498.ALSO:In processes for the separation of a body from its solution in a liquid by extracting it in counter current with a solvent insoluble in the liquid in a series of extractions in each of which the solvent and solution are intimately mixed and the mixture decanted e.g. as described in Specification 307,868, [Class 81 (i), Disinfecting &c.], the extractions are effected at or above the boiling point of the mixture and the substances are mixed in each stage by bubbling the vapours rising from one stage through the liquids in the next stage.  A 25 per cent solution of acetic acid is extracted with methyl cyclohexanone in a column A having a number of double plates each comprising a decantation plate (D1 . . Dn) and an ordinary bubble plate (P1 . . Pn) connected by overflow pipes T1 . . Tn and M1 . . Mn.  Vapours rising from the plate P1 pass upwards through a pipe c2 and through a bubble cap into the liquid on the Plate P2.  Each decanting plate, e.g., D2 is connected to a receiver R2 by three conduits b2, c2, d2 by which the levels of the upper and lower layers and the pressures in the chambers R2 and A are equalized. The lower layer may be extracted from the receiver R2 by a conduit C2 having an adjustable outlet f and may be raised to the mixing plate P3 above it by injection of steam or other known means.  The dilute acetic acid is supplied through a pipe g and methyl cyclohexanone through a pipe S, while concentrated acid dissolved in the solvent is recovered through a pipe a and is freed from solvent in any known manner.  The dehydration of a 10 per cent acetic acid solution by means of isopropyl acetate is described with reference to a modified column in which a column as shown in the Figure is superposed on a column forming dehydrating and separating zones.  The composition of the <PICT:0380928/III/1> mixture which runs on to the first plate of the dehydration zone is 91,8 per cent isopropyl acetate, 4,4 per cent acetic acid and 3,8 per cent water and the isopropyl acetate being present in sufficient amount to eliminate the water, the dehydrated mixture descends into the separation zone and then into a small auxiliary column whence the acid and acetate are separated readily by their difference in boiling points.  Examples are also given of the dehydration of acetic acid by a mixture of ethyl acetate and benzene, and also by amyl alcohol.  The process is suitable for the extraction of tars from pyroligneous liquors, and to the extraction of perfumes, and to the esterification of aliphatic acids as described in Specification 378,498 [Group IV].